Circuit board and mobile electronic apparatus

ABSTRACT

A circuit board in which the attachment strength of a frame member to a substrate can be improved, and a mobile electronic apparatus are provided. 
     A circuit board  16  has: a substrate  28;  plural electronic components  29  which are mounted on the substrate  28;  and a frame member  30  which is attached to the substrate  28  so as to surround the electronic components  29.  A resin portion  36  is formed by a resin which is filled into the frame member  30.  The circuit board  16  has: a lower bent portion  41  (contact portion) which is disposed in a basal end portion  38 B of a wall portion  38  of the frame member  30  along the substrate  28;  and a raised portion  42  which is disposed in an outer end portion  41 A of the lower bent portion  41.

TECHNICAL FIELD

The present invention relates to a circuit board in which pluralelectronic components are mounted on a substrate, and a frame member isattached to the substrate so as to surround the electronic components,and also to a mobile electronic apparatus such as a mobile telephone.

BACKGROUND ART

A circuit board which is accommodated in a mobile terminal such as amobile telephone comprises a substrate on which a circuit pattern isformed, and plural electronic components which are mounted on thesubstrate by fixing terminal portions to the circuit pattern throughsolder.

Recently, a circuit board is proposed in which the mounting strength ofan electronic component is improved by a resin portion (underfill) thatcovers a part of the body of the electronic component, and that is inclose contact with a substrate (see Patent Reference 1).

Patent Reference 1 can be applied also to the case where the mountingstrength is improved by a resin portion that collectively covers thewhole of plural electronic components mounted on a substrate.

Patent Reference 1: Japanese Patent No. 3,241,669 DISCLOSURE OF THEINVENTION Problem that the Invention is to Solve

In the case where the mobile terminal is dropped, or where an externalforce such as twisting or bending is applied to a case, however, thereis the possibility that the frame member is separated from thesubstrate, or that a lid member is dropped off from the frame member.

The invention has been conducted in order to solve the above-discussedproblem. It is an object of the invention to provide a circuit board inwhich the attachment strength of a frame member to a substrate can beimproved, and a mobile electronic apparatus.

Means for Solving the Problem

The circuit board of the invention comprises: a substrate; pluralelectronic components which are mounted on the substrate; a frame memberwhich is attached to the substrate so as to surround the electroniccomponents; a contact portion which is disposed on the frame member, andwhich is in contact with the substrate along the substrate; and a resinportion which covers the electronic components inside the frame member.

Here, as the contact portion, for example, a plate-like portion may beexemplified.

The contact portion may be disposed in the inside or outside of theframe member, or in one or both of the inside and the outside, and isnot required to be continuous along the periphery of the frame member.

Such a contact portion may be disposed integrally with a wall portionconstituting the frame member by bending a lower end portion of the wallportion toward the inside or the outside, or a separate plate-likemember may be connected to the lower end portion of the wall portion byadequate means such as welding.

In such a circuit board, the frame member is attached to a mountingsurface of the substrate through the contact portion, and hence thecontact area with respect to the substrate can be increased as comparedwith the prior art.

In the circuit board, therefore, the attachment strength of the framewith respect to the substrate can be improved, and also the bendingstrength and the twisting strength can be improved.

In the circuit board of the invention, the contact portion is disposedwhile being directed to an outside of the frame member, and the circuitboard comprises a raised portion in which a part of the contact portionis raised in a vertical direction with respect to the substrate.

Here, as the raised portion, a structure in which a plate-like orcolumnar portion is erected from an arbitrary place of the contactportion in parallel to, for example, the wall portion may beexemplified. However, the raised portion is not required to becontinuous along the periphery of the wall portion.

The vertical direction means a direction which is identical with theheight direction of the electronic components extended from the mountingsurface of the substrate, and the raised angle to the mounting surfaceof the substrate, the raised dimension, and the like are arbitrary.

The raised portion may be disposed integrally with the contact portionby bending an end portion of the contact portion, or a separateplate-like member may be connected to an end portion of the contactportion or an arbitrary position by adequate means such as welding.

In such a circuit board, the contact portion which is disposed whilebeing directed toward the outside of the frame member comprises theraised portion. When a lib disposed on the rear side of a cover of acase constituting a mobile electronic apparatus is engaged with theraised portion, for example, relative positioning between the circuitboard and the cover can be easily performed, and the circuit board canbe integrated with the frame member through the frame member, wherebythe strength of the mobile electronic apparatus can be improved.

In such a circuit board, when another electronic component such as adisplay device to be stacked on the circuit board is engaged with theraised portion, relative positioning between the circuit board and theother electronic component can be easily performed because of theabove-mentioned reason, and the strength improvement due to theintegration of the circuit board and the other electronic component isattained.

Alternatively, the circuit board of the invention comprises: asubstrate; plural electronic components which are mounted on thesubstrate; a frame member which is attached to the substrate so as tosurround the electronic components; and a resin portion which covers theelectronic components inside the frame member, and a part of the framemember comprises a contact portion which is in contact with thesubstrate along the substrate.

In the circuit board of the invention, a part of the frame membercomprises a raised portion which is raised in a vertical direction withrespect to the substrate.

In the circuit board of the invention, a part of the frame member has arecess which is in contact with the substrate along the substrate.

The circuit board of the invention is characterized in that anelectrically conductive adhesive agent is applied to an upper face ofthe resin portion.

In such a circuit board, the conductive adhesive agent is applied to theupper face of the resin portion. Therefore, even in the case where a lidmember is not attached to the frame member, for example, a shieldingproperty is obtained, and, in the case where a lid member is attached tothe frame member, electrically conductivity between the frame member andthe lid member is obtained, and hence the shielding property can befurther improved.

The mobile electronic apparatus of the invention employs theabove-described circuit board, and comprises: a substrate; pluralelectronic components which are mounted on the substrate; a frame memberwhich is attached to the substrate so as to surround the electroniccomponents; a contact portion which is disposed on the frame member, andwhich is in contact with the substrate along the substrate; a resinportion which covers the electronic components inside the frame member;a raised portion in which a part of the contact portion is raised in avertical direction with respect to the substrate; and a cover portionbetween the frame member and the raised portion.

According to the configuration, the frame member and a cover can beintegrated with each other, and the dropping strength of the mobileelectronic apparatus can be further improved.

Effects of the Invention

According to the circuit board and mobile electronic apparatus of theinvention, the contact portion which is in surface contact with themounting surface of the substrate is disposed in the frame member, andhence an effect that the attachment strength of the frame member to thesubstrate can be improved is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a mobile electronic apparatuscomprising the circuit board (first embodiment) of the invention.

FIG. 2 is a section view taken along the line A-A in FIG. 1.

FIG. 3 is an exploded section view along the line B-B in FIG. 1.

FIG. 4 is a section view taken along the line B-B in FIG. 1.

FIG. 5 is an exploded perspective view showing a frame member and lidmember of the circuit board of the first embodiment.

FIG. 6 is an enlarged view of a portion C in FIG. 5.

FIG. 7 is a section view showing the circuit board of the firstembodiment.

FIG. 8 is a section view showing the circuit board (second embodiment)of the invention.

FIG. 9 is a perspective view showing Modification 1 of the circuit boardof the invention.

FIG. 10 is a perspective view showing Modification 2 of the circuitboard of the invention.

FIG. 11 is a perspective view showing Modification 3 of the circuitboard of the invention.

FIG. 12 is a perspective view showing Modification 4 of the circuitboard of the invention.

FIG. 13 is a perspective view showing Modification 5 of the circuitboard of the invention.

FIG. 14 is a perspective view showing Modification 6 of the circuitboard of the invention.

FIG. 15 is a perspective view showing Modification 7 of the circuitboard of the invention.

FIG. 16 is a perspective view showing Modification 8 of the circuitboard of the invention.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

10 mobile terminal (mobile electronic apparatus)

16, 60 circuit board

28 substrate

29 electronic component

30 frame member

31 opening of frame member

34 lid member

36 resin portion

36A upper face of resin portion

38 wall portion of frame member

38B basal end portion

41 lower bent portion (contact portion)

42 raised portion

61 electrically conductive adhesive agent

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

Hereinafter, a circuit board of an embodiment of the invention will bedescribed with reference to the drawings.

As shown in FIG. 1, a mobile terminal 10 which is a mobile electronicapparatus of a first embodiment comprises an upper case (case) 11, and alower case 12 which is rotatably coupled to the upper case 11 through acoupling portion 13. The mobile terminal is configured so that, when theupper case 11 and the lower case 12 are relatively moved through thecoupling portion 13, it is possible to select a mobile state where theupper case 11 and the lower case 12 are stacked with each other, or anextended state (the illustrated state) where the upper case 11 and thelower case 12 are separately placed.

As shown in FIGS. 2 to 4, the upper case 11 is configured by a frontcover 14 and a rear cover 15, and a circuit board 16 is accommodatedbetween the front cover 14 and the rear cover 15.

An opening portion 17 is formed in the surface 14A of the front cover14, a displaying portion 19 is placed so as to be exposed through theopening portion 17, and the surface 14A of the front cover 14 and thedisplaying portion 19 are covered by a panel 20 (see FIGS. 3 and 4).

The rear cover 15 is formed into a two-layer structure by a resin-madecover 22 and a metal-made cover 23.

In the upper case 11, as shown in FIG. 1, an earpiece portion 21 isdisposed above the displaying portion 19. In the lower case 12, anoperating portion 24 and a mouthpiece portion 25 are provided on thesurface.

Hereinafter, the circuit board 16 of the invention will be describedwith reference to FIGS. 2 to 7.

As shown in FIGS. 2 to 4, the circuit board 16 comprises: a substrate28; plural electronic components 29 which are mounted on a mountingsurface of the substrate 28; a frame member 30 which is attached to thesubstrate 28 so as to surround the electronic components 29; a lidmember 34 which closes an opening 31 of the frame member 30; and anelectrically conductive adhesive agent 35 (see FIG. 7) which isinterposed between the frame member 30 and the lid member 34. A resinportion 36 is formed by a resin which is filled into the frame member30.

As shown in FIG. 5, the frame member 30 has: a wall portion 38 which isformed into, for example, a substantially rectangular shape; an upperbent portion 39 which is disposed in an upper end portion 38A (see alsoFIGS. 6 and 7) of the wall portion 38; a lower bent portion 41 (contactportion) which is disposed in a basal end portion 38B (see also FIGS. 6and 7) of the wall portion 38; and a raised portion 42 which is disposedin an outer end portion 41A of the lower bent portion 41.

The wall portion 38 is formed into a substantially rectangular shape by:a pair of vertical side walls 38C, 38D which are opposed to each other;one lateral side wall 38E which is disposed on one-end sides of the pairof vertical side walls 38C, 38D; and another lateral side wall 38F whichis disposed on other-end sides of the pair of vertical side walls 38C,38D.

Basal end portions 38B of the pair of vertical side walls 38C, 38D, andbasal end portions 38B of the pair of lateral side walls 38E, 38F buttagainst the substrate 28.

Namely, the basal end portions 38B of the pair of vertical side walls38C, 38D, and the basal end portions 38B of the pair of lateral sidewalls 38E, 38F constitute the basal end portion 38B of the wall portion38.

Projections 44 are disposed at regular intervals on the pair of verticalside walls 38C, 38D and the pair of lateral side walls 38E, 38F.

As shown in FIG. 7, the projections 44 are portions which are projectedtoward the outside of the frame member 30.

The reason why the projections 44 are disposed on the vertical sidewalls 38C, 38D and the lateral side walls 38E, 38F will be describedlater.

The upper bent portion 39 is disposed in the whole periphery of theupper end portion 38A of the wall portion 38. As shown in FIG. 7, theupper bent portion 39 is extended in parallel with the substrate 28 fromthe upper end portion 38A toward the inside of the frame member 30.

The lower bent portion 41 is disposed in the basal end portions 38B ofthe pair of vertical side walls 38C, 38D in the wall portion 38. Asshown in FIG. 7, the lower bent portion 41 is extended along themounting surface of the substrate 28 from the basal end portion 38Btoward the outside of the frame member 30.

The configuration in which the lower bent portion 41 is disposed alongthe mounting surface of the substrate 28 allows the lower bent portion41 to function as a contact portion which is in surface contact with themounting surface of the substrate 28.

Therefore, the contact area of the frame member 30 with respect to thesubstrate 28 can be increased, and the attachment strength of the frame30 with respect to the substrate 38 can be improved.

Moreover, the bending strength and the twisting strength can be improvedby the increase of the contact area of the frame member 30 with respectto the substrate 28.

The raised portion 42 is disposed in the whole area of the outer endportion 41A of the lower bent portion 41.

The raised portion 42 is disposed so as to be raised in a directionalong which it separates from the outer end portion 41A of the lowerbent portion 41 along the thickness direction of the substrate 28.

According to the configuration, when a groove portion 14B of the frontcover 14 constituting the upper case 11 is engaged with the raisedportion 42 as shown in FIGS. 3 and 4, the front cover 14 can beintegrated with the raised portion 42, i.e., the frame member 30, andthe strength can be improved.

The engagement of the groove portion 14B with the raised portion 42 maybe performed by pressingly inserting the raised portion 42 into thegroove portion 14B, or by loosely inserting the raised portion 42 intothe groove portion 14B via an air gap.

The displaying portion 19 (see FIG. 1) which is stacked on the framemember 30 is engaged with the raised portion 42, whereby the strengthcan be improved.

The raised portion 42 plays also a role of a rib, so that the strengthcan be further improved.

In addition, when the front cover 14 is engaged with the raised portion42, the positioning of the front cover 14 with respect to the framemember 30 can be easily performed.

In the specification, a region defined by the wall portion 38, the lowerbent portion 41, and the raised portion 42 is configured as a recess.

As shown in FIG. 5, the lid member 34 is put on the frame member 30. Thelid member 34 has: a side wall 46 which is formed into a rectangularshape that is slightly larger than the frame member 30; and a lid body47 which is disposed on an upper end portion 46A of the side wall 46.

In the side wall 46, opening portions 48 are formed at the regularintervals. When the lid member 34 is put on the frame member 30, theopening portions 48 are engaged with the above-described projections 44(see FIG. 7).

Specifically, when the lid member 34 is put on the frame member 30, theopening portions 48 are fitted on the projections 44, and the openingportions 48 are engaged with the projections 44.

The lid body 47 has plural protruding portions 50 which are protruded atarbitrary places of the lid body 47 toward the inside of the lid member34 (i.e., the inside of the frame member).

As shown in FIG. 7, each of the protruding portions 50 has: a hangingportion 51 which is formed into a cylindrical shape; an extended portion52 which is extended toward the outside from a lower end portion 51A ofthe hanging portion 51.

The hanging portions 51 are projected so as to be directed from the lidbody 47 in the thickness direction of the substrate 28 toward thesubstrate 28.

The extended portions 52 are extended along the face direction of thesubstrate 28.

Namely, the hanging portions 51 and the extended portions 52 are formedso that their sections have a substantially L-like shape, and embeddedinto the resin portion 36. Since the section shapes of the hangingportions 51 and extended portions 52 are formed into a substantiallyL-like shape, the protruding portions 50 can have a shape which hardlydrops off from the resin portion 36.

The protruding portions 50 having a substantially L-like shape aredisposed on the lid member 34, and embedded into the resin portion 36,whereby, when the resin filled into the frame member 30 is cured, theresin is caused to contract, so that the protruding portions 50 arepulled by the resin portion 36 toward the frame member 30.

As a result, the lid member 34 is pulled toward the frame member 30, andhence the lid member 34 can be made in close contact with the framemember 30 in following to the contraction of the resin portion 36.

In this way, the close contact of the lid member 34 with the framemember 30 can improve the attachment strength of the lid member 34 withrespect to the frame member 30, and further improve the shieldingproperty.

Moreover, the interposition of the electrically conductive adhesiveagent 35 between the frame member 30 and the lid member 34 can stillfurther improve the shielding property.

As another effect, the embedding of the protruding portions into theresin portion enables the substrate, the frame member, the lid member,and the resin portion to be integrated with one another, therebyattaining a synergistic effect for rigidification of the circuit board.

Second Embodiment

Next, a circuit board 60 of a second embodiment will be described withreference to FIG. 8.

In the circuit board 60 of the second embodiment shown in FIG. 8, anelectrically conductive adhesive agent 61 is applied to the upper face36A of the resin portion 36. The other configuration is identical withthat of the circuit board 16 of the first embodiment.

The electrically conductive adhesive agent 61 is an adhesive agent whichis identical with the electrically conductive adhesive agent 35 of thefirst embodiment.

In the circuit board 60, the application of the electrically conductiveadhesive agent 61 to the upper face 36A of the resin portion 36 canstill further improve the shielding property.

Next, Modifications 1 to 4 of the raised portion 42 and lower bentportion 41 of the first and second embodiments will be described withreference to FIGS. 9 to 12.

In Modification 1 shown in FIG. 9, the raised portion 42 is not disposedin the whole area of the lower bent portion 41, but disposed in a partof the lower bent portion 41.

In Modification 2 shown in FIG. 10, the raised portion 42 and the lowerbent portion 41 are not disposed in the whole area of the vertical sidewall 38C, but disposed in a part of the vertical side wall 38C.

In Modification 3 shown in FIG. 11, the raised portion 42 is notdisposed, and only the lower bent portion 41 is disposed.

In Modification 4 shown in FIG. 12, the raised portion 42 is notdisposed, and only the lower bent portion 41 is disposed so that thelower bent portion 41 is not disposed in the whole area of the verticalside wall 38C, but disposed in a part of the vertical side wall 38C.

According to Modifications 1 to 4, it is possible to achieve the sameeffects as the circuit boards 16, 60 of the first and secondembodiments.

Next, Modifications 5 to 8 of the protruding portions 50 of the firstand second embodiments will be described with reference to FIGS. 13 to16.

In Modification 5 shown in FIG. 13, protruding portions 65 are disposedin place of the protruding portions 50 of the first and secondembodiments.

Each of the protruding portions 65 has: a plate-like hanging portion 65Awhich is protruded so as to be directed from the lid body 47 in thethickness direction of the substrate 28 toward the substrate 28; and anextended portion 65B which is extended so as to be directed from a lowerend portion of the hanging portion 65A along the face direction of thesubstrate 28.

The hanging portion 65A and the extended portion 65B are formed into asubstantially L-like shape which hardly drops off from the resin portion36.

In Modification 6 shown in FIG. 14, protruding portions 66 are disposedin place of the protruding portions 50 of the first and secondembodiments.

Each of the protruding portions 66 has: a plate-like hanging portion 65Awhich is protruded so as to be obliquely directed from the lid body 47in the thickness direction of the substrate 28 toward the substrate 28;and a plate-like extended portion 65B which is obliquely protruded froma lower end portion of the hanging portion 65A in a direction oppositeto the hanging portion 65A.

The hanging portion 65A and the extended portion 65B are formed into asubstantially dog-leg shape which hardly drops off from the resinportion 36.

In Modification 7 shown in FIG. 15, protruding portions 67 are disposedin place of the protruding portions 50 of the first and secondembodiments.

Each of the protruding portions 67 has: a plate-like hanging portion 67Awhich is protruded so as to be directed from the lid body 47 in thethickness direction of the substrate 28 toward the substrate 28; and aextended portion 67B which is protruded obliquely upward with respect tothe substrate 28 from a lower end portion of the hanging portion 67A.

The hanging portion 67A and the extended portion 67B are formed into asubstantially V-like shape which hardly drops off from the resin portion36.

In Modification 8 shown in FIG. 16, protruding portions 68 are disposedin place of the protruding portions 50 of the first and secondembodiments.

Each of the protruding portions 68 has: a plate-like hanging portion 68Awhich is protruded so as to be directed from the lid body 47 in thethickness direction of the substrate 28 toward the substrate 28; and anextended portion 68B which is extended in both directions so as to bedirected from a lower end portion of the hanging portion 68A along theface direction of the substrate 28.

The hanging portion 68A and the extended portion 68B are formed into asubstantially T-like shape which hardly drops off from the resin portion36.

According to Modifications 5 to 8, it is possible to achieve the sameeffects as the circuit boards 16, 60 of the first and secondembodiments.

In the above-described first and second embodiments, the example inwhich the lower bent portion 41 is extended toward the outside of theframe member 30 has been described. The invention is not restricted tothis. The lower bent portion 41 may be extended toward the inside of theframe member 30.

Moreover, the example in which the lower bent portion 41 is disposed inthe pair of vertical side walls 38C, 38D in the wall portion 38 has beendescribed. The invention is not restricted to this. The lower bentportion may be disposed in the whole periphery of the wall portion 38.

The shapes and configurations of portions such as the frame member 30,the lid member 34, the resin portion 36, and the raised portion 42 whichhave been exemplified in the first and second embodiments are notrestricted to them, and may be adequately changed.

INDUSTRIAL APPLICABILITY

The invention is preferably applied to a circuit board in which pluralelectronic components are mounted on a substrate, and a frame member isattached to the substrate so as to surround the electronic components,and also to a mobile electronic apparatus.

1. A circuit board comprising: a substrate; plural electronic componentswhich are mounted on said substrate; a frame member which is attached tosaid substrate so as to surround said electronic components; a contactportion which is disposed on said frame member, and which is in contactwith said substrate along said substrate; and a resin portion whichcovers said electronic components inside said frame member, wherein saidcontact portion is disposed while being directed to an outside of saidframe member, and said circuit board comprises a raised portion in whicha part of said contact portion is raised from said substrate.
 2. Acircuit board according to claim 1, wherein an electrically conductiveadhesive agent is applied to an upper face of said resin portion.
 3. Amobile electronic apparatus wherein a circuit board according to claim 1is employed.
 4. A circuit board comprising: a substrate; pluralelectronic components which are mounted on said substrate; a framemember which is attached to said substrate so as to surround saidelectronic components; and a resin portion which covers said electroniccomponents inside said frame member, a part of said frame membercomprising a contact portion which is in contact with said substratealong said substrate, wherein a part of said frame member comprises araised portion which is raised from said substrate.
 5. A circuit boardaccording to claim 4, wherein a part of said frame member has a recesswhich is in contact with said substrate along said substrate.
 6. Acircuit board according to claim 2, wherein an electrically conductiveadhesive agent is applied to an upper face of said resin portion.
 7. Amobile electronic apparatus wherein a circuit board according to claim 2is employed.
 8. A mobile electronic apparatus comprising: a substrate;plural electronic components which are mounted on said substrate; aframe member which is attached to said substrate so as to surround saidelectronic components; a contact portion which is disposed on said framemember, and which is in contact with said substrate along saidsubstrate; a resin portion which covers said electronic componentsinside said frame member; a raised portion in which a part of saidcontact portion is raised to from said substrate; and a cover portionbetween said frame member and said raised portion.